Talkin' Sales Books

Which sales-related books have helped the most in your careers?

I make a point of trying to read a new sales book once every three months. So far it's been some Jill Konrath, Blount, Keenan... the usual suspects.

Half the time, though, I feel like I should be reading up on human behavior - something that helps with selling but not made for sellers (you know what I mean?). Good example: Made to Stick by the Heath brothers.

Any good recc's for either inside or outside the sales industry? Any examples of situations where they helped?

(If this has already been posted then my b.)